If you are interested in a prescient look at how climate change will impact geopolitics:

https://www.amazon.com/Climate-Wars-Fight-Survival-Overheats...

The author intersperses nonfiction summaries (from 2011, so a bit dated) with fictional accounts of geopolitical conflict.

Super scary but eye opening.

I loved "Climate Wars" by Gwynne Dyer: https://www.amazon.com/Climate-Wars-Fight-Survival-Overheats...

If you are looking for a fictional take, check out "The Water Knife" by Paolo Bacigalupi: https://www.amazon.com/Water-Knife-Paolo-Bacigalupi/dp/08041...

This book, a mix of research and speculation (chapter by chapter) was helpful to me in making the abstract threat of climate change real:

https://www.amazon.com/Climate-Wars-Fight-Survival-Overheats...

It will definitely change geopolitics for the foreseeable future.

This book outlines various geopolitical climate change reactions. http://www.amazon.com/Climate-Wars-Fight-Survival-Overheats/...

The last scenario talks about, if I recall correctly, the oceans becoming more welcoming to bacteria that produce hydrogen sulfide. Sorry, I don't remember the details, but will update tonight from the book at home if I remember.